Switchboards, panelboards, and motor controller enclosures having one or more access doors may include electrically-energized components therein. UL 347 specifies that mechanical interlocks should be provided on certain of these enclosures in order to prevent operators from opening such equipment access doors when the equipment being protected is still electrically energized. This minimizes safety hazards to the operators.
In conventional mechanical interlocks used in the past to accomplish a locking function on such doors, a locking protrusion (pin) has been welded directly to the door. This locking protrusion interfaces with a conventional door interlock mechanism. However, because all doors are not perfectly manufactured or assembled, the mechanical interlock may not always function properly.
Accordingly, a need exists to improve the mechanical interlock so as to improve performance thereof.